在jsp页面向文件中写入信息时,文件路径如何处理?
2011-05-26 13:34
645 查看
这两天做Web项目时需要向配置文件中写入信息,可是调试良久未果。具体情况如下:
Web项目testproject中需要向src下的一个配置文件system.properties中写入信息。我在页面中通过String realPath = application.getRealPath("/")方式可以获取当前项目发布后的根路径(即D:/ToolSoft/apache-tomcat-6.0.32/webapps/testproject/)。而那个配置文件在项目下的路径为WEB-INF/classes/system.properties。我想以new File(realPath + “WEB-INF/classes/system.properties”);的方式创建一个文件对象并向其中写入信息,可是程序执行时出错。
我觉得应该是那个路径和java里面的路径分隔符不一致的问题。于是,有人建议我直接在创建File对象时把路径写成固定的。可我觉得这样不好,因为项目重新发布时还要修改该路径。上网找了一下,有人说用File.separator可以解决问题,但我试了半天也没有能够解决。
无奈,最后向我一个老师求助。老师回复说【首先确定你的路径是否正确,其二,试试双斜杠,有些在处理路径的时候要这样,不认识单斜杠】。按照老师的指点又尝试一番,最后终于解决问题。
其实也比较简单,我把相关代码发上来供大家参考!
项目结构:
index.jsp页面源码:
Code:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page import="org.test.TestServlet,java.io.*"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<%
//读取配置文件
Properties props = new Properties();
try
{
InputStream in = TestServlet.class.getClassLoader()
.getResourceAsStream("system.properties");
props.load(in);
} catch (IOException e)
{
System.out.println("配置文件读取失败!");
}
//获取配置信息
String author = props.getProperty("author");
if (author == null)
author = "";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<center>修改系统信息<br/>
<form action="test" method="post">
<!-- 获取当前项目发布后在服务器的真实根路径 -->
<input type="hidden" name="realPath"
value="<%=application.getRealPath("/")%>" />
<!-- 显示配置文件中的配置信息 -->
author: <input type="text" name="author" value="<%=author%>" />
<br/>
<input type="submit" value="submit" />
</form>
</center>
</body>
</html>
web.xml文件内容:
Code:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>TestServlet</servlet-name>
<servlet-class>org.test.TestServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>TestServlet</servlet-name>
<url-pattern>/test</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
TestServlet.java文件内容:
Code:
package org.test;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Properties;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class TestServlet extends HttpServlet
{
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
// Sets the character encoding (MIME charset) of the response being sent to the client
response.setCharacterEncoding("UTF-8");
String realPath = request.getParameter("realPath");
String author = request.getParameter("author");
// 我原来两种错误的写法:
// String filePath = realPath + "WEB-INF/classes/systeminfo.properties";
// String filePath = realPath.replaceAll("//", "/") + "WEB-INF/classes/systeminfo.properties";
// 下面是正确的写法:
String filePath = realPath + "WEB-INF//classes//system.properties";
Properties prop = new Properties();
try
{
File f = new File(filePath);
OutputStream fos = new FileOutputStream(f);
prop.setProperty("author", author);
// 将此 Properties 表中的属性列表(键和元素对)写入输出流。
prop.store(fos, "Update 'author' value");
response.getWriter().write("系统信息更新成功!");
} catch (IOException e)
{
System.err.println("Visit " + filePath + " for updating author value error");
e.printStackTrace();
}
}
}
system.properties文件内容:
Code:
#Update 'author' value
#Thu May 26 13:00:59 CST 2011
author=Tom
因为是一个测试例子,所以项目中的流程十分简单,我就不多废话了!
最后附上该测试例子源码(可直接导入MyEclipse 8.5):
http://download.csdn.net/source/3314443
Web项目testproject中需要向src下的一个配置文件system.properties中写入信息。我在页面中通过String realPath = application.getRealPath("/")方式可以获取当前项目发布后的根路径(即D:/ToolSoft/apache-tomcat-6.0.32/webapps/testproject/)。而那个配置文件在项目下的路径为WEB-INF/classes/system.properties。我想以new File(realPath + “WEB-INF/classes/system.properties”);的方式创建一个文件对象并向其中写入信息,可是程序执行时出错。
我觉得应该是那个路径和java里面的路径分隔符不一致的问题。于是,有人建议我直接在创建File对象时把路径写成固定的。可我觉得这样不好,因为项目重新发布时还要修改该路径。上网找了一下,有人说用File.separator可以解决问题,但我试了半天也没有能够解决。
无奈,最后向我一个老师求助。老师回复说【首先确定你的路径是否正确,其二,试试双斜杠,有些在处理路径的时候要这样,不认识单斜杠】。按照老师的指点又尝试一番,最后终于解决问题。
其实也比较简单,我把相关代码发上来供大家参考!
项目结构:
index.jsp页面源码:
Code:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page import="org.test.TestServlet,java.io.*"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<%
//读取配置文件
Properties props = new Properties();
try
{
InputStream in = TestServlet.class.getClassLoader()
.getResourceAsStream("system.properties");
props.load(in);
} catch (IOException e)
{
System.out.println("配置文件读取失败!");
}
//获取配置信息
String author = props.getProperty("author");
if (author == null)
author = "";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<center>修改系统信息<br/>
<form action="test" method="post">
<!-- 获取当前项目发布后在服务器的真实根路径 -->
<input type="hidden" name="realPath"
value="<%=application.getRealPath("/")%>" />
<!-- 显示配置文件中的配置信息 -->
author: <input type="text" name="author" value="<%=author%>" />
<br/>
<input type="submit" value="submit" />
</form>
</center>
</body>
</html>
web.xml文件内容:
Code:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>TestServlet</servlet-name>
<servlet-class>org.test.TestServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>TestServlet</servlet-name>
<url-pattern>/test</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
TestServlet.java文件内容:
Code:
package org.test;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Properties;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class TestServlet extends HttpServlet
{
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
// Sets the character encoding (MIME charset) of the response being sent to the client
response.setCharacterEncoding("UTF-8");
String realPath = request.getParameter("realPath");
String author = request.getParameter("author");
// 我原来两种错误的写法:
// String filePath = realPath + "WEB-INF/classes/systeminfo.properties";
// String filePath = realPath.replaceAll("//", "/") + "WEB-INF/classes/systeminfo.properties";
// 下面是正确的写法:
String filePath = realPath + "WEB-INF//classes//system.properties";
Properties prop = new Properties();
try
{
File f = new File(filePath);
OutputStream fos = new FileOutputStream(f);
prop.setProperty("author", author);
// 将此 Properties 表中的属性列表(键和元素对)写入输出流。
prop.store(fos, "Update 'author' value");
response.getWriter().write("系统信息更新成功!");
} catch (IOException e)
{
System.err.println("Visit " + filePath + " for updating author value error");
e.printStackTrace();
}
}
}
system.properties文件内容:
Code:
#Update 'author' value
#Thu May 26 13:00:59 CST 2011
author=Tom
因为是一个测试例子,所以项目中的流程十分简单,我就不多废话了!
最后附上该测试例子源码(可直接导入MyEclipse 8.5):
http://download.csdn.net/source/3314443
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